Improvement in overstitch sewing-machines



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W A POLMATEER OVER-STITCH SEWINGMAGH1NE- Y Patented N 23, 1875.

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W. A. POLMATEER. OVER-STITCH SEWING-MACHINE. l N0 170,390, Patented Nov. 23,1875.

N.PTERS, FHOTO-UTHOGRAPHER. WASHINGTON, D. C.

UNTTED STATES PATENT QFFIGE; l

, 4 l WILLIAM A. POLMATEER, OF JOHNSTOWN, NEW YORK.

IMPROVEMENT IN OVERSII'ITCH SEWING-MACHINES.

Specification forming part of Letters Patent No. 170,390, dated November 23, 1875; application filed July 28, 1875.

To allwhom ivf-may concern:

Be it known that I, WILLIAM A. POLMA- TEER, of Johnstown, county of Fulton and State of New York, have invented an Improved Overstitch Sewing-Machine, of which the following' is a specication, reference being had to the accompanying drawings, formv ing` part hereof.

My invention relates ro that class of sewingmachines which form what is calledfan overstitc-h either on the edge or on a fold of fabric 5 and consists in the peculiar and special devices, mechanism, and combinations hereinafter particularly described.

' Figure l is an end elevation of a sewingmachine vembodying my invention. Fig. 2 is a similar view of the same, showing the mechanism which operates the needle-bar and loophook. Fig. 3 is a front elevation of the parts shown in Fig'. l. Fig. 4 is au enlarged detail view of the loop-hook; and Fig. 5 is a detail view ofthe stitch.

Similar letters of reference indicate similar parts.

B is the needle-bar, working in bearings in the frame a and plate A, and is thrown by the crank-pin b, fixed in the eccentric E, and. provided with the bowl c, working in the irregular groove el, in the plate e, which is fixed on the needle-bar, as shown, and slides on the waysw. His the loop-hook,formed, as shown,` in Fig. 4, with the shank s, the curved wing or heel w extending from one side at its lower extremity, as shown, and the pointed hook h projectingfbrward and somewhat upward from the said wing or heel, and off the center of the same. The said loop-hook H is attached to the lever L, and is thrown by the bar D, to which the lever is pivoted at j, said bar being operated by the fork F, adjusted upon the eccentric E, which is fixed on the main shaft S, the said eccentric E being provided with the plate p on its outer side,- which forms a rim or ange, as shown, preventing the disarrangement of the fork. The loop-hook H is given its proper lateral movements to take up the loop and carry it under the needle in proper position and hold it there while the needle descends through it, and then to leave the loop, by means of the curved arm g of the lever L, provided with the ear h', engaging with the rim and side of the compound cam G, which is formed as shown, the coil-spring'k, which extends from the spring-arm m to the lower, arm vof the lever L,.acting to keep the arm g in continuous contact with the said cam.

The feed device consists of the two rollers R and'R, the upper roller, R, turning loosely erned in its motion by the brake leaf-,spring 1 which is clamped upon it,V and is revolved through the distance of each stitch, carrying the fabric with it, by the clutch c', which engages with the lateral ange f on the roller,

operated by the clutch-lever l', pivoted 011 the short shaft b', and actuated by the oscillating cam g and the coil-springs S and s. The `cam` g is keyed to the shaft G, and is given 'its oscillating motion by means of a pitman connecting the shaft G to the main shaft S. The short shaft b', carrying the lower roller and its operating devices, is mounted on the' lever C', which is pivoted to the bed-plate at e', and is provided with the Vcoil-spring D. By

'means of an upward pressure exerted on the outward arm h" of this said lever, the lower feed-roller is separated from the upper roller lt, so that the fabric may be readily inserted between them. This pressure maybe con-A veniently applied through suitablev mechanism vby the foot or knee of the operator.

,The thread tis passed irst over an ordinary tension, T, and then through a guide-loop, m', which is made adjustable in the plate A by means of the set-screw t', as shown, in order that the length of thread unreeled at each stitch may be properly regulated, then through the guide-loop n', which is fixed iu the upper end of the needle-bar, as shown, and which acts, the thread bein gheld taut at the needle, as hereafter shown, to unreel the thread required for each successive stitch by the upward movement of the said needle-bar, then down through the spring-tension k', which is as shown, to a pin, 1", set in theneedle-bar, and extending through and working in theslotted opening u' in the plate A. This teni sion-spring A being carried up and down by the movement of the needle-bar, crosses back y and forth over the plate r, thus alternately pressing upon and releasing the thread t, which passes over said plate, and operating to hold the thread taut at the needle while theneedle is going down through the fabric and returning, but permitting the slack thread held by the tension-spring k to pass to the needle, when the needle is above the fabric, and a new stitch is about to be made.

The operation of my machine in stitching is as follows:` The needle-bar being depressed to its lowest limit inthe position shown in the drawing, and the needle passed down through the fabric, the loop-hook His also at its lowest. limit, as shown, which is below the cloth, and back of and alittle to one side of the needle. The revolution ofthe main shaft S now raises the needle-bar and draws the needle upward through the fabric, and the thread on the outside ofthe needle, just above'the eye, forms a loop, which the point h of the loop-hook enters. The loop-hook, during the further ascent of the needle, carries the loop on its point upward over the edge of the fabric, and passes somewhat forward, so as to tighten or draw up the loop formed on the previous stitch, and

then over the fabric, and directly under the needle in its downward course.

By means of the curved heel w of the loophook, the loop is held distended under the needle-point, so that the needlet descends through it on entering the fabric just behind the hook in the concave of the heel w. The hook is then withdrawn from the loop and the needle passes down through the loop and fabric, and returns upward through the same loop, while the loop -hook is .again `thrown down to its lowest limit, ready to catch the next loop.

' By means of the crank-pin b, with its collar c working in the irregular groove d in platee, fixed on the needle-bar, the said needle-bar remains stationary at its lowest limit on its descent through the loop and fabric, while the said pin and collar traverse the said groove from about the position shown in Fig. 2 to the quarter, during which time the loop-hook is being thrown from its position to the rear of the needle on leaving the loop, down to its lowest limit.

An overstitch on the edges or on a fold of the fabric, such as 'shown `in Fig. 5, is thus formed by the loops, which are formed below the fabric, and carried over the fabric across the edge or fold and tied, by the thread` being passed down and up through each loop. As each successive loop` is brought up by the hook, the feed-roller R carries the fabric along thelength ofone stitch, and the length ofthe stitch to -be taken may be regulated by the set-screw B', which bears against the small arm or pin d in the lever l', and hence permits a longer or shorter swingof the said lever in operating the clutch c. V

My machine is adapted to forman overstitch on both light and heavy fabrics and materials. When heavy fabric is being -stitched the tension leaf-spring A' should be used as described, but when light fabric, such as knit goods, is stitched, this tension will not be necessary, the tension lo" being then sufficient to holdthe thread taut enough.

I do not intend to clainLherein the peculiar overstitch made by my machine, as herein shown and described, reserving to myself the right to make the said stitch the subject hereafter of a separate and disnct application for Letters Patent.

Having `thus described my invention, what I claim as new, and desire to secure by Letters Patent, is

1. In an overstitch sewing-,1:nachi11e, the loop-hook H, having the shank s, the curved heel w, and hook-point h, as described, and for the purpose specified. i

2. The combination of the needle-bar B, carrying the needle n, having `plate e, irreguf lar groove d, and crank-pin b, with collar c, the loop-hook H, lever L, compound cam Gr, coilspring 7c, bar D, fork 'F, and eccentric E, as described. Y

3. The combination, with the needle-bar B and needle n, carrying thread tof the tension T, adjustable guide-loop m', guide-loop n', tension-spring 7c', pin p, plate r, and tensionspring A', as described.

4. The combination of the upper feed-roller R, lower feed-roller R', brake leaf-spring l, clutch c', clutch-lever l', oscillating cam g', coil-springs S and s', short shaft b, lever C', and spring D', as described.

WM. A. POLMATEER. 

